Diabetes in Ontario

TLDR

Accurate information about the magnitude and distribution of diabetes can inform policy and support health care evaluation. The study linked physician service claims and hospital discharge abstracts from Ontario’s administrative databases to construct a retrospective cohort and applied two diabetes identification algorithms (1‑claim and 2‑claim) to estimate prevalence and incidence. The 1‑claim and 2‑claim algorithms had sensitivities of 90 % and 86 % and specificities of 92 % and 97 %, with prevalence rising from 3.2 % in 1993 to 4.5 % in 1998 and incidence remaining stable, indicating that diabetes prevalence in Ontario is increasing and exceeds self‑reported rates. Administrative data can be used to establish population‑based incidence and prevalence of diabetes.

Abstract

Accurate information about the magnitude and distribution of diabetes can inform policy and support health care evaluation. We linked physician service claims (PSCs) and hospital discharge abstracts (HDAs) to determine diabetes prevalence and incidence.A retrospective cohort was constructed using administrative data from the national HDA database, PSCs for Ontario (population 11 million), and registries carrying demographics and vital statistics. All HDAs and PSCs bearing a diagnosis of diabetes (ICD9-CM 250) were selected for 1991-1999. Two previously reported algorithms for identification of diabetes were applied as follows: "1-claim" (any HDA or PSC showing diabetes) and "2-claim" (one HDA or two PSCs within 2 years showing diabetes). Incident cases were defined as individuals who met the criteria for diabetes for the first time after at least 2 years of observation. For validation, diagnostic data abstracted from primary care charts (n=3,317) of 57 randomly selected physicians were linked to the administrative data cohort, and sensitivity and specificity were calculated.-In 1998, 696,938 individuals met the 1-claim criteria and 528,280 met the 2-claim criteria. Sensitivity for diabetes was 90 and 86%; for the 1- and 2-claim algorithms, specificity was 92 and 97%, respectively, and positive predictive values were 61 and 80%, respectively. Using the 2-claim algorithm, the all-age prevalence increased from 3.2% in 1993 to 4.5% in 1998 (6.1% in adults). Incidence remained stable.Administrative data can be used to establish population-based incidence and prevalence of diabetes. Diabetes prevalence is increasing in Ontario and is considerably higher than self-reported rates.